Essential Fatty Acids

Essential fatty acids (EFAs) are considered as a category of poly-unsaturated fatty acids (PUFA), these are the classes of lipids which are not produced in our body and therefore, they have to be obtained from the dietary food sources and topical application. There are two categorization of EFAs i.e. omega-6 and omega-3 fatty acids. The prototype of omega-6 fatty acid is Linoleic Acid and that of omega-3 is α-linolenic acid (ALA). Linoleic acid (LA) is one of the most significant and abundant PUFA present in the outer most layer of epidermis, the stratum corneum (SC) [1, 2, 3]. Linoleic acid (LA) is found to be blend with two classes of ceramides [1, 4, 5]. The presence of LA in stratum corneum helps in strengthening the barrier functioning of the skin [5].

Essential Fatty Acids Role in Skin Diseases

Transepidermal Water Loss (TEWL), impairment of reproduction and sex drive and growth retardation [6, 7]. Similar effects were observed in humans with essential fatty acids deficiency which manifested clinically as dermatitis and increased water loss across the skin [8, 9].

The deficiency of essential fatty acids is characterized by hyper-proliferation of skin and effect the functioning of skin and its appearance along with increase in Transepidermal Water Loss (TEWL). The signs of dermatitis may not be visible for many weeks to months, whereas chemical manifestations are apparent even after days to weeks [10].

Essential Fatty Acids Helpful in Skin Diseases

In experimental models study’s [5,11,12,14] to evaluate the significance of PUFA models, EFA deficiency was induced which was completely devoid of EFAs. While doing this, the ability of specific fatty acids in relieving cutaneous and biochemical effects of EFA deficiency were accessed. The supplementation oils which are rich in omega-6 fatty acid corrected the symptoms of deficiency [11, 12]. The preparation of purified Linoleic acid (LA)  can also improve the barrier functioning [5,14]. These above mentioned studies clearly made the role of Linoleic acid (LA) evident in the health of skin and stability of waterproof barrier.

Topical administration of Essential Fatty Acids (EFA) can reduce the symptoms of deficiency in humans [9, 15] or animals [5, 14]. The application of sunflower seed oil which contain omega-6 fatty acid increased the Linoleic acid (LA)  content of epidermis, reduced the scale formation of skin, Transepidermal Water Loss (TEWL) was normalized after a few weeks, even the bio-chemical symptoms of Essential Fatty Acids (EFA)  deficiency were corrected which postulated that delivery can eventually travel to the skin [15]. Topical application is the best route for effective treatment of skin disease [34] because during ingestion the Essential Fatty Acids (EFA)  are oxidized in liver before reaching the peripheral tissues, around 60 percent of Alpha Linoleic acid (ALA) and 20 percent of Linoleic acid (LA) is oxidized in liver [16].

The essential fatty acids can even protect the skin against the harmful ultraviolet radiations of the sun as suggested by the evidences from various studies [17, 18]. Topically applied Alpha Linoleic acid (ALA) may also reduce the UV response of radiations. In a human trial study, sardine oil contain omega 3 fatty acid were applied to the forearm topically [19] which greatly reduced the ultra-violet B induced erythema as compared the side on which on oil was applied. Similar to this, hairless mice were also protected against the skin damage induced by ultraviolet radiation on application of omega 3 fatty acid topically on their skin [20]. Another animal study reported that not only topical but also the dietary accumulation of Alpha Linoleic acid (ALA)  can reduce the erythema induced by UVB radiations in hairless mice [21].

References

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  2. Chapkin RS, Ziboh VA. Inability of skin enzyme preparations to biosynthesize arachidonic acid from linoleic acid. Biochem Biophys Res Commun. 1984;124:784-792.  
  3. Chapkin RS, Ziboh VA, Marcelo CL, Voorhees JJ. Metabolism of essential fatty acids by human epidermal enzyme preparations: evidence of chain elongation. J Lipid Res. 1986;27:945-954
  4. Gray GM, Yardley HJ. Lipid compositions of cells isolated from pig, human, and rat epidermis. J Lipid Res. 1975;16:434-440.
  5. .  Hansen HS, Jensen B. Essential function of linoleic acid esterified in acylglucosylceramide and acylceramide in maintaining the epidermal water permeability barrier. Evidence from feeding studies with oleate, linoleate, arachidonate, columbinate and alpha-linolenate. Biochim Biophys Acta. 1985;834:357-363.  
  6. Burr GO, Burr MM. A new deficiency disease produced by the rigid exclusion of fat from the diet. J Biol Chem. 1929;82:345-367.
  7. Burr GO, Burr MM. On the nature and role of the fatty acids essential in nutrition. J Biol Chem. 1930;86:587-621.
  8. Hansen AE, Haggard ME, Boelsche AN, Adam DJ, Wiese HF. Essential fatty acids in infant nutrition. III. Clinical manifestations of linoleic acid deficiency. J Nutr. 1958;66:565-576.  
  9. Prottey C, Hartop PJ, Press M. Correction of the cutaneous manifestations of essential fatty acid deficiency in man by application of sunflower-seed oil to the skin. J Invest Dermatol. 1975;64:228-234
  10. Jeppesen PB, Hoy CE, Mortensen PB. Essential fatty acid deficiency in patients receiving home parenteral nutrition. Am J Clin Nutr. 1998;68:126-133.  
  11. Chapkin RS, Ziboh VA, McCullough JL. Dietary influences of evening primrose and fish oil on the skin of essential fatty acid-deficient guinea pigs. J Nutr. 1987;117:1360-1370.  
  12. Ziboh VA, Chapkin RS. Biologic significance of polyunsaturated fatty acids in the skin. Arch Dermatol. 1987;123:1686a-1690.
  13. Hansen HS, Jensen B. Essential function of linoleic acid esterified in acylglucosylceramide and acylceramide in maintaining the epidermal water permeability barrier. Evidence from feeding studies with oleate, linoleate, arachidonate, columbinate and alpha-linolenate. Biochim Biophys Acta. 1985;834:357-363.
  14. Elias PM, Brown BE, Ziboh VA. The permeability barrier in essential fatty acid deficiency: evidence for a direct role for linoleic acid in barrier function. J Invest Dermatol. 1980;74:230-233.  
  15. Press M, Hartop PJ, Prottey C. Correction of essential fatty-acid deficiency in man by the cutaneous application of sunflower-seed oil. Lancet. 1974;1:597-598.  
  16. Sinclair AJ, Attar-Bashi NM, Li D. What is the role of alpha-linolenic acid for mammals? Lipids. 2002;37:1113-1123.
  17. Pilkington SM, Watson RE, Nicolaou A, Rhodes LE. Omega-3 polyunsaturated fatty acids: photoprotective macronutrients. Exp Dermatol. 2011;20:537-543.
  18. Sies H, Stahl W. Nutritional protection against skin damage from sunlight. Annu Rev Nutr. 2004;24:173-200.
  19. Puglia C, Tropea S, Rizza L, Santagati NA, Bonina F. In vitro percutaneous absorption studies and in vivo evaluation of anti-inflammatory activity of essential fatty acids (EFA) from fish oil extracts. Int J Pharm. 2005;299:41-48.  (PubMed)
  20. Jin XJ, Kim EJ, Oh IK, et al. Prevention of UV-induced skin damages by 11,14,17-eicosatrienoic acid in hairless mice in vivo. J Korean Med Sci. 2010;25:930-937.  (PubMed)
  21. Takemura N, Takahashi K, Tanaka H, et al. Dietary, but not topical, alpha-linolenic acid suppresses UVB-induced skin injury in hairless mice when compared with linoleic acids. Photochem Photobiol. 2002;76:657-663.
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